In the production of motion pictures, a motion picture camera must often be moved from one position to another. The camera movements may require a change in camera position, camera angle or camera elevation. The camera movement must be performed smoothly, as even small amounts of vibration of the camera can result in unsatisfactory filming results, due to shaky or erratic recorded images. Similar requirements must often be met in the case of TV studio productions, e.g. predefined camera movements that are to be performed along the studio floor.
Camera dollies and pedestals have long been used to support and move motion picture cameras. Typically, a camera dolly has four wheels or pairs of wheels on a platform or chassis having a square shaped wheel base. The wheels may be attached to the chassis via articulated legs, or the wheels may be directly pivotally attached to the chassis. The camera dolly must support and enable maneuvering of the camera with a minimum of vibration or shock, to avoid degrading the filmed image quality. Consequently, a camera dolly must be designed, manufactured and maintained with precision, and the dolly may be placed on rails or tracks on the studio floor to provide an even and smooth rolling surface.
Regular camera dollies roll over rail tracks that have joint cuts between rail sections perpendicular to the direction of elongation of the rail track. A drawback with this is that, at some point each wheel will roll over these joint cuts. Therefore, there are points where the wheel is only supported by cuts between two rail sections. This joint has the potential to create a bump or jerk as the wheel roll over it. As mentioned above, the dolly of a TV or motion picture camera must be very smooth otherwise the bump or jerk will be seen on the resulting recording/film.
A currently available solution for mitigating this drawback is micro-accurate engineering in the process of manufacturing the ends of rail sections, often using heavy and expensive metal work machinery. Typically, prior art rail sections have a solid rod that protrudes from the end of one section and a round hollow receptor in the end of the other section. These are called the male and female ends of the sections and they slot together and kept tight with a locking system. If there is any gap or if the two sections are not absolutely straight, the joints will cause slight jerks when the dolly platform wheels roll over them. To minimize this bump or jerk, much time and effort is used during the setup of the dolly system so as to ensure the camera does not feel any bump.
However, such prior art solutions further require rail tracks of relatively large dimensions, and when being placed on top of a studio floor, creates an obstacle protruding up to 20 cm from the floor surface. On the other hand, an immersion of such a rail track to avoid it being an obstacle would require a deep trench in the floor, which would represent a permanent damage in the floor structure, and limit the possibility mobility, for reorganizing the studio and for using the studio for other purposes than TV production.
Another problem with camera dollies on rail tracks is the well-known rail wheel squeal which is a noise that is generated when a dolly moves more or less rapidly along rail track curves. Needless to say, studio noise is particularly important to avoid in TV studios because of the nature of the indoor environment of reflections and small distances from sound source to sound recorders.
Therefore there is a need for arrangements related to a dolly system that are capable of resolving or at least mitigating at least some of the abovementioned drawbacks.
The prior art includes U.S. Pat. No. 6,557,775 where a dolly system is described, which has drawbacks as discussed above.